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About High Performance GEOS-Chem

GEOS-Chem with the high performance option (GCHP) is the next generation of GEOS-Chem. It uses a distributed memory capability designed to enable efficient scaling across many cores, and thus enable finer resolution simulations. GCHP has the advantage of using a cubed sphere geometry that enables more accurate transport and eliminates the polar singularity inherent to lat-lon grids. With these advances you can still run the model on a single machine at coarse resolution if you choose to do so.

If you are working on a project using GCHP, please add your name and project description to the GCHP projects list. Also help us pool performance information across systems by contributing your GCHP run information on our GCHP Timing Tests page.

If you would like to stay informed of GCHP developments, please join the GEOS-Chem High Performance Working Group mailing list and subscribe to GCHP notifications on GitHub. We also encourage you to join our GCHP Slack workspace to interact with other users. If you would like receive help or start or participate in conversations about GCHP, please use the GCHP GitHub issue tracker. You may also contact the GEOS-Chem Support Team if you have questions or need assistance, or reach out the GCHP Working Group Co-Chairs.

GCHP Wiki Guide

Getting Started

• Online Manual

Version Information

• Current Version
• Newsletters
• Model Development Priorities
• Older Versions (v11-02 and prior)

Validation and Performance

• Benchmark History
• Timing Information

Community

• GCHP Working Group
• Slack Workspace

Troubleshooting

• GCHP GitHub Issue Tracker
• Verifying a Successful Run
• GEOS-Chem 12 known issues and bugs

Help Resources and Quick Links

• Frequently Asked Questions
• Tools for Regridding and Data Analysis
• Introduction to git

GCHP Cubed Sphere Grid Geometry

GCHP uses a cubed sphere grid rather than the traditional lat-lon grid used in GEOS-Chem Classic. While regular lat-lon grids are typically designated as ΔLat ⨉ ΔLon (e.g. 4⨉5), cubed sphere grids are designated by the side-length of the cube. In GCHP we specify this as CX (e.g. C24 or C180). The simple rule of thumb for determining the roughly equivalent lat/lon for a given cubed sphere resolution is to divide the side length by 90. Using this rule you can quickly match C24 with 4x5, C90 with 1 degree, C360 with quarter degree, and so on.

Harvard graduate student Jiawei Zhuang created the following interactive illustrations demonstrating key features of the GCHP cubed sphere geometry:

• Step-by-step illustration on how to create a cubed sphere grid
• Comparison of different cubed sphere map projections
• Creating a "stretched" cubed sphere to get fine resolution in a selected region of the world

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